dunno about digital, but in chemical-based photography, diffusing the light source, while allowing sufficient light for the contrast on the images is a key in product photography.
You might see press photographers with flash attachments with a piece of white cardboard taped to them, angling the flash UP into the paper, which then diffuses (spreads) the light out and helps avoid the hard, contrasty images and shadow lines.
If you are using artificial light, a large piece of white cardboard opposite the lamp, or light source, will bounce the light back and fill it in the shadows on the side opposite the light.
You might also use a transluscent sheet of paper.
The outside shots are so much more clear because the sun is WAY high and the light is directly down, diffused throughout the image. Additionally, a "grey" card used to set the light availability and appropriate aperature and shutter speed is almost always essential for copy work, or fine product work.
(any 12 in AK blems?)
Nice work.